Idelalisib has its chemical name as 5-fluoro-3-phenyl-2-[(1S)-1-(9H-purin-6-ylamino)propyl]-4(3H)-quinazolinone, and its structure is shown as formula (I):

Idelalisib (Brand Name as Zydelig) is a selective phosphoinositide 3-kinase δ (PI3K-δ, P110-δ) inhibitor developed by Gilead Sciences, Inc. On Jul. 23, 2014, US Food and Drug Administration (FDA) approved Idelalisib for three indications: relapsed chronic lymphocytic leukemia (CLL) in combination with rituximab, relapsed follicular B-cell non-Hodgkin lymphoma (FL) and relapsed small lymphocytic lymphoma (SLL) as a single prescription. The FDA has accelerated approval for the latter two, and patients have received at least two systemic treatments previously.
Idelalisib is the first oral, selective phosphoinositide 3-kinase δ (PI3K-δ, P110-δ) inhibitor that entered the market. P110-δ is involved in the change of the immune environment of B lymphocytes and plays a key role in the activation, proliferation, survival and migration of this type of tumor cells. The approval of Idelalisib brings a new option after Ibrutinib for the treatment of chronic lymphocytic leukemia. In the United States, the number of patients with chronic lymphocytic leukemia is second largest among adult patients with leukemia, and it is expected to increase more than 15,000 new patients in 2014. The development of new drugs for chronic lymphocytic leukemia, including Idelalisib and Ibrutinib, is expected to turn chronic lymphocytic leukemia from death sentences into a manageable chronic disease. Of course, the market for chronic lymphocytic leukemia has also grown, and the analyst of Bloomberg News forecast the market for chronic lymphocytic leukemia will soon climb to $9 billion.
U.S. Pat. No. 8,865,730 reported several polymorphs and solvates of Idelalisib, including Form I, Form II, Form III (mixed water and isopropanol solvate), Form IV (N,N-dimethylformamide solvate), Form V (dimethylsulfoxide solvate), and Form VII (mixed water and ethanol solvate). The polymorph in marketed Idelalisib Tablet is a mixture of Form I and Form II, and the dosages are 100 mg and 150 mg. As an antitumor drug, its dosage is relatively high, and other four polymorphs are solvate, which are not suitable for pharmaceutical use.
The solid form of drugs directly affects the solubility of active pharmaceutical ingredients, dissolution and bioavailability of formulation. In order to improve the bioavailability of drugs and reduce dosage and side effects, it is necessary to develop new solid forms of drug. Besides crystalline forms, solid forms of drugs can also be amorphous.
An amorphous form of drug is a special form of solid substance and has important application in preparation of drug. Current studies have shown that the amorphous form of many drugs have good stability and can be used in the development of general solid dosage form.
In addition, there are a few polyamorphous phenomena for drugs, and each amorphous form has different stability, and therefore searching for an amorphous form with good stability is also one of the ways to develop a better solid state of drugs.